Hybrid vehicles are operated using power from an internal combustion engine and from a battery. In particular, hybrid vehicles are designed to efficiently combine and use power of the internal combustion engine and a motor.
For example, as illustrated in FIG. 1, a hybrid vehicle includes an engine 10, a motor 20, an engine clutch 30, a transmission 40, a differential gear 50, a battery 60, an integrated starter-generator (ISG) 70, and wheels 80. The engine clutch 30 controls power transmission between the engine 10 and the motor 20, and the integrated starter-generator (ISG) 70 starts the engine 10 or generates electric power by output torque of the engine 10.
As further shown, the hybrid vehicle includes: a hybrid control unit (HCU) 200 which controls overall operation of the hybrid electric vehicle; an engine control unit (ECU) 110 which controls operation of the engine 10; a motor control unit (MCU) 120 which controls operation of the motor 20; a transmission control unit (TCU) 140 which controls operation of the transmission 40; and a battery control unit (BCU) 160 which manages and controls the battery 60.
The battery control unit 160 may also be referred to as a battery management system (BMS). The integrated starter-generator 70 may also be referred to as a starting/generating motor or a hybrid starter-generator.
The hybrid vehicle may be operated in three different modes: a driving mode such as an electric vehicle (EV) mode solely using power of the motor 20; a hybrid electric vehicle (HEV) mode using torque of the engine 10 as main power and torque of the motor 20 as auxiliary power; and a regenerative braking (RB) mode while braking or when the vehicle runs by inertia. In the RB mode, braking and inertial energy are collected through power generation of the motor 20, and the battery 60 is charged with the collected energy.
When the hybrid vehicle runs, torque of the motor is set in order to satisfy driver's demand torque corresponding to the operation degree of an accelerator pedal, and then control to output the torque of the motor is performed.
However, when the output torque of the motor exceeds torque corresponding to charge or discharge limiting power of a battery, the battery may be over-charged or over-discharged, which may damage the battery, as illustrated in FIG. 2.
Accordingly, by considering a state of the battery, a scheme that sets a maximum or minimum torque limiting value not to exceed the charge or discharge limiting power value of the battery is requested.
The above information disclosed in this Background section is solely for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.